Files Context Menu too limited
Yes, the blender file browser is limited, but there are some workarounds for both of the things you mentioned.

Editing images. Blender has an option in the image editor to “edit externally,“ which can be set in user preferences to open images in whatever your favorite image editor program is (GIMP in my case), and then you can reload the image from the source to update it when you’re done.
Filtering. The file browser itself has search box in the header at the top that does not look in subdirectories. Try this for quick filtering of large directories.